ITEM 1A.     RISK FACTORS

In addition to the other factors discussed elsewhere in this report and in other reports we file with the SEC, the following factors could cause our actual results or events to differ materially from those contained in any forward-looking statements made by us or on our behalf. In addition, other risks and uncertainties not presently known to us or that we currently deem immaterial may impair our business and operations. If any of the following risks or such other risks occur, it could adversely affect our business, operating results and financial condition, as well as cause the value of our common stock to decline.

Risks Related to Our Business

If we need but are unable to obtain additional funding to support our operations, we could be required to reduce our research and development activities or curtail our operations and it may lead to uncertainty about our ability to continue to operate as a going concern.

We have expended substantial funds to discover and develop our drug candidates and additional substantial funds will be required for further development, including preclinical testing and clinical trials, of any product candidates we develop internally. Additional funds will be required to manufacture and market any products we own or retain rights to that are approved for commercial sale. Because the successful development of our products is uncertain, we are unable to precisely estimate the actual funds we will require to develop and potentially commercialize them.

We have historically funded our operations from up-front fees and license and milestone payments received under our drug partnerships, the sale of equity securities and debt provided by our credit facilities and our recent convertible debt offering. We believe that our cash, cash equivalents and marketable securities as of June 30, 2013 , and the anticipated receipt of up-front and milestone payments under new and existing partnerships, will enable us to continue to fund operations in the normal course of business for at least the next 12 months. However, we will continue to depend on funding our operations from these sources for the foreseeable future. Our ability to obtain additional funding when needed, changes to our operating plans, our existing and anticipated working capital needs, the acceleration or modification of our planned research and development activities or expenditures, increased expenses or other events may affect our need for additional capital in the future and may require us to seek additional funding sooner than anticipated.

Our ability to successfully raise sufficient funds through the sale of debt or equity securities or from debt financing from lenders when needed is subject to many risks and uncertainties and, even if we are successful, future equity issuances would result in dilution to our existing stockholders. We also may not successfully consummate new partnerships that provide for additional up-front fees or milestone payments, or we may not earn milestone payments under such

partnerships when anticipated, or at all. Our ability to realize milestone or royalty payments under existing partnership agreements and to enter into new partnering arrangements that generate additional revenue through up-front fees and milestone or royalty payments is subject to a number of risks, many of which are beyond our control. In August 2013, we reduced our workforce by approximately 20% as part of our efforts to fund our discovery organization with strategic collaborations and focus internally on progressing our hematology and oncology programs to later stage development. If we are unable to generate enough revenue from our existing or new partnerships when needed or secure additional sources of funding, it may be necessary to significantly reduce our current rate of spending through further reductions in staff and delaying, scaling back or stopping certain research and development programs, including more costly Phase 2 and Phase 3 clinical trials on our wholly-owned or co-development programs as these programs progress into later stage development. These events may result in an inability to maintain a level of liquidity necessary to continue operating our business and the loss of all or a part of the investment of our stockholders in our common stock and may result in a reduction in the value of our 3.00% convertible senior notes due 2020, or the 2020 notes. In addition, if we are unable to maintain certain levels of cash and marketable securities, our obligations under our loan agreement with Comerica Bank may be accelerated.

We have a history of operating losses and may not achieve or sustain profitability.

We have incurred significant operating and net losses and negative cash flows from operations since our inception. As of June 30, 2013 , we had an accumulated deficit of $632.7 million . We had net losses of $61.9 million , $23.6 million , and $56.3 million for the fiscal years ended June 30, 2013 , 2012 and 2011 , respectively. We expect to incur additional losses and negative cash flows in the future, and these losses may continue or increase in part due to anticipated levels of expenses for research and development, particularly clinical development and expansion of our clinical and scientific capabilities to support ongoing development of our programs. As a result, we may not be able to achieve or maintain profitability.

We may not receive royalty or milestone revenue under our partnership agreements for several years, or at all.

Much of our current revenue is non-recurring in nature and unpredictable as to timing and amount. Several of our partnership agreements provide for royalties on product sales. However, because none of our drug candidates have been approved for commercial sale, our drug candidates are at early stages of development and drug development entails a high risk of failure, we may never realize much of the milestone revenue provided for in our partnership agreements and we do not expect to receive any royalty revenue for several years, if at all. Similarly, drugs we select to commercialize ourselves or partner for later stage co-development and commercialization may not generate revenue for several years, or at all.

We or our partners may choose not to commercialize a drug candidate at any time during development, which would reduce or eliminate our potential return on investment for that drug.

At any time, we or our partners may decide to discontinue the development of a drug candidate or not to commercialize a candidate. If we terminate a program in which we have invested significant resources, we will not receive any return on our investment and we will have missed the opportunity to have allocated those resources to potentially more productive uses. If one of our partners terminates a program, we will not receive any future milestone payments or royalties relating to that program under our partnership agreement with that party. Even if one of our drug candidates receives regulatory approval for marketing, physicians or consumers may not find that its effectiveness, ease of use, side-effect profile, cost or other factors make it effective in treating disease or more beneficial than, or preferable to, other drugs on the market. Additionally, third-party payors, such as government health plans and health insurance plans or maintenance organizations, may choose not to include our drugs on their formulary lists for reimbursement. As a result, our drugs may not be used or may be used only for restricted applications.

Our partners have substantial control and discretion over the timing and the continued development and marketing of drug candidates we have licensed to them and, therefore, over the timing and whether we receive anticipated milestone payments and/or royalties.

Our partners have significant discretion in determining the efforts and amount of resources that they dedicate to our partnerships and, therefore, whether we will receive milestone payments and any royalties when anticipated, or at all. Our partners may decide not to proceed with clinical development or commercialization of a particular drug candidate for any number of reasons that are beyond our control, even under circumstances where we might have continued such a program. In addition, our receipt of milestone payments and royalties from our partners depends on their abilities to establish the safety and efficacy of our drug candidates, obtain regulatory approvals and achieve market acceptance of products developed from our drug candidates. We also depend on our partners to manufacture clinical scale quantities of

some of our drug candidates and would depend on them in the future for commercial scale manufacture, distribution and direct sales. In addition, we may not be apprised of the development or commercialization activities or strategies of our partners and, as a result, our assumptions regarding the anticipated receipt of milestone payments or royalties may be incorrect.

We face additional risks in connection with our partnerships, including the following:

We may not be successful in entering into additional out-license agreements on favorable terms, which may adversely affect our liquidity or require us to change our spending priorities on our proprietary programs.

We are committing significant resources to create our own proprietary drug candidates and to build a commercial-stage biopharmaceutical company. We have built our clinical and discovery programs through spending $580.2 million from our inception through June 30, 2013 . In fiscal 2013 , we spent $59.4 million in research and development for proprietary programs, compared to $56.7 million and $63.5 million for fiscal years 2012 and 2011 , respectively. Many of our proprietary drug discovery programs are in an early stage of development and are unproven. Our ability to continue to fund our planned spending on our proprietary drug programs and in building our commercial capabilities depends to a large degree on up-front fees, milestone payments and other revenue we receive as a result of our partnered programs. To date, we have 10 active partner-funded clinical programs, and we plan to continue initiatives during fiscal 2014 to partner select clinical and preclinical stage programs to obtain additional capital or fund further development.

We may not be successful, however, in entering into additional out-licensing agreements with favorable terms, including up-front, milestone, royalty and/or license payments and the retention of certain valuable commercialization or co-promotion rights, as a result of factors, many of which are outside of our control. These factors include:

If we are unable to enter into out-licensing agreements and realize milestone, license and/or up-front fees when anticipated, it may adversely affect our liquidity and we may be forced to curtail or delay development of all or some of our proprietary programs, which in turn may harm our business and the value of our stock. In addition, insufficient funds may

require us to relinquish greater rights to product candidates at an earlier stage of development or on less favorable terms to us or holders of our securities than we would otherwise choose to obtain funding for our operations.

We may not out-license our proprietary programs at the most appropriate time to maximize the total value or return of these programs to us.

A critical aspect of our business strategy is to out-license drug candidates for further development, co-development and/or commercialization to obtain the highest possible value while also evaluating earlier out-licensing opportunities to maximize our risk-adjusted return on our investment in proprietary research. Because the costs and risk of failure of bringing a drug to market are high, the value of out-licensing a drug candidate generally increases as it successfully progresses through clinical trials.

We may choose or be forced to out-license a drug candidate or program on terms that require us to relinquish commercial or market rights or at a point in the research and development process that does not provide as great a value or return than what might have been obtained if we had further developed the candidate or program internally. Likewise, we may decline, or be unable to obtain favorable, early out-licensing opportunities in programs that do not result in a commercially viable drug, which could leave the resulting program with little or no value even though significant resources were invested in its development. Our inability to successfully out-license our programs on favorable terms could materially adversely affect our results of operations and cash flows.

Many of our drug candidates are at early stages of development and we may not successfully develop a drug candidate that becomes a commercially viable drug.

The drug discovery and development process is highly uncertain and we have not developed, and may never develop, a drug candidate that ultimately leads to a commercially viable drug. Many of our drug candidates are in the early stages of development, and our most advanced drug candidate is in early Phase 3 studies. We do not have any drugs approved for commercial sale. Before a drug product is approved by the FDA for commercial marketing, it is tested for safety and effectiveness in clinical trials that can take up to six years or longer. Promising results in preclinical development or early clinical trials may not be predictive of results obtained in later clinical trials. A number of pharmaceutical companies have experienced significant setbacks in advanced clinical trials, even after obtaining promising results in earlier preclinical studies and clinical trials. At any time, we, the FDA or an IRB, may temporarily or permanently stop the trial, for a variety of reasons, principally for safety concerns. We or our partners may experience numerous unforeseen events during, or as a result of, the clinical development process that could delay or prevent our drug candidates from being approved, including:

As our product candidates advance to later stage clinical trials, it is customary that various aspects of the development program, such as manufacturing, formulation and other processes, and methods of administration, are altered to optimize the candidates and processes as part of scale-up necessary for later stage clinical trials, approval and commercialization. These changes may not produce the intended optimization, including production of drug substance and drug product of a quality and in a quantity sufficient for Phase 3 clinical stage development or for commercialization, which may cause delays in the initiation or completion of clinical trials and greater costs. We may also need to conduct "bridging studies" to demonstrate comparability between newly manufactured drug substance and/or drug product for commercialization relative to previously manufactured drug substance and/or drug product for clinical trials. Demonstrating comparability may require us to incur additional costs or delay initiation or completion of clinical trials and, if unsuccessful, could require us to complete additional preclinical studies or clinical trials.

Our capital requirements could significantly increase if we choose to develop more of our proprietary programs internally.

We believe that the maximum value for certain proprietary drug candidates is best achieved by retaining the rights to develop and commercialize the candidate and not seeking a partner or by waiting until later in the development process to seek a partner to co-develop and commercialize or co-promote a product. It is difficult to predict which of our proprietary programs are likely to yield higher returns if we elect to develop them further before seeking a partner or to not seek a partner at all as a result of many factors, including the competitive position of the product, our capital resources, the perceived value among potential partners of the product and other factors outside of our control. Therefore, we may undertake and fund, solely at our expense, further development, clinical trials, manufacturing and marketing activities for a greater number of proprietary candidates than we planned, which may not result in a greater return to Array than if we had chosen to out-license those programs. In addition, we may choose not to out-license certain of our proprietary programs if we are unable to do so on terms that are favorable to us. As a result, our requirements for capital could increase significantly. We may be unable to raise additional required capital to fund this additional development on favorable terms, or at all, however, or we may be required to substantially reduce our development efforts, which would delay, limit or prevent our ability to commercialize and realize revenue from our drug candidates.

Because we rely on a small number of partners for a significant portion of our revenue, if one or more of our major partners terminates or reduces the scope of its agreement with us, our revenue may significantly decrease.

A relatively small number of partners account for a significant portion of our revenue. Amgen, Celgene, Genentech, Novartis and Oncothyreon accounted for 16% , 21% , 11% , 26% and 14% , respectively, of our total revenue for fiscal 2013 . In fiscal 2012 , Amgen, Celgene, Genentech and Novartis accounted for 34% , 7% , 41% and 16% , respectively, of our total revenue. We expect that revenue from a limited number of partners, including Genentech, Novartis and Celgene, will account for a large portion of our revenue in future quarters. In general, our partners may terminate their contracts with us upon 60 to 180 days’ notice for a number of reasons or no reason, which would eliminate future milestone or royalty revenue under the collaboration.

If our drug discovery and development programs do not progress as anticipated, our revenue, stock price and the value of the 2020 notes could be negatively impacted.

We estimate the timing of a variety of preclinical, clinical, regulatory and other milestones for planning purposes, including when a drug candidate is expected to enter clinical trials, when a clinical trial will be completed, when and if additional clinical trials will commence, or when an application for regulatory approval will be filed. We base our estimates on facts that are currently known to us and on a variety of assumptions that may prove not to be correct for a variety of reasons, many of which are beyond our control. For example, delays in the development of drugs by Array or our partners may be caused by regulatory or patent issues, negative or inconclusive interim or final results of on-going clinical trials, scheduling conflicts with participating clinics and the availability of patients who meet the criteria for and the rate of patient enrollment in, clinical trials and the development priorities of our partners. In addition, in preparing these estimates we rely on the timeliness and accuracy of information and estimates reported or provided to us by our partners concerning the timing, progress and results of clinical trials or other development activities they conduct under our collaborations with them. If we or our partners do not achieve milestones when anticipated, or if our partners choose to terminate a program, we may not achieve our planned revenue and our stock price could decline. In addition, any delays in obtaining approvals to market and sell drugs may result in the loss of competitive advantages in being on the market sooner than, or in advance of, competing products, which may reduce the value of these products and the potential revenue we receive from the eventual sale of these products, either directly or under agreements with our partners.

We may not be able to recruit and retain the experienced scientists and management we need to compete in the drug research and development industry.

We have 265 employees as of June 30, 2013 , and our future success depends upon our ability to attract, retain and motivate highly-skilled scientists and management. Our ability to achieve our business strategies, including progressing drug candidates through later stage development or commercialization, attracting new partners and retaining, renewing and expanding existing partnerships, depends on our ability to hire and retain high caliber scientists and other qualified experts, particularly in clinical development and commercialization. We compete with pharmaceutical and biotechnology companies, contract research companies and academic and research institutions to recruit personnel and face significant competition for qualified personnel, particularly clinical development personnel. We may incur greater costs than anticipated, or may not be successful, in attracting new scientists or management or in retaining or motivating our existing personnel. In addition, we periodically review our existing workforce in light of the current and anticipated needs of our business and may make strategic changes to its size and scope in an effort to use our capital more efficiently.

Our future success also depends on the personal efforts and abilities of the principal members of our senior management and scientific staff to provide strategic direction, manage our operations and maintain a cohesive and stable environment. In particular, we rely on the services of Ron Squarer, our Chief Executive Officer; Dr. Mike Needle, our Chief Medical Officer; Dr. Kevin Koch, our President and Chief Scientific Officer; Dr. David L. Snitman, our Chief Operating Officer and Vice President, Business Development; R. Michael Carruthers, our Chief Financial Officer; and John R. Moore, our Vice President and General Counsel. We have employment agreements with each of these employees that are terminable upon 30 days’ prior notice.

Risks Related to Our Clinical Development Activities and Obtaining Regulatory Approval for Our Programs

We have limited clinical development and commercialization experience.

One of our business strategies is to develop select drug candidates through later stage clinical trials before out-licensing them to a pharmaceutical or biotechnology partner for further clinical development and commercialization and to commercialize select drug candidates ourselves. We began a Phase 3 trial in June 2013 on MEK162 in low-grade serous ovarian cancer, but we have not previously conducted a Phase 3 or later stage clinical trial ourselves, nor have we commercialized a drug. We have limited experience conducting clinical trials and obtaining regulatory approvals and we may not be successful in some or all of these activities. In addition, in deciding to pursue development of ovarian cancer in the Phase 3 MILO study, we relied on broad based activity that has been shown for MEK162 in other indications and known prior results with other inhibitors, including MEK inhibitors that have shown activity in ovarian cancer. Consequently, we do not have direct clinical information that MEK162 will be effective in treating the proposed patient population. We have no experience as a company in the sales, marketing and distribution of pharmaceutical products and do not currently have a sales and marketing organization. We expect to expend significant amounts to recruit and retain high quality personnel with clinical development experience. Developing commercialization capabilities would be expensive and time-consuming and could delay any product launch, and we may never be able to develop this capacity. To the extent we are unable to or determine not to develop these resources internally, we may be forced to rely on third-party clinical investigators, or clinical research or marketing organizations, which could subject us to costs and to delays that are outside our control. If we are unable to establish adequate capabilities independently or with others, we may be unable to generate product revenues for certain candidates.

If we or our partners fail to adequately conduct clinical trials, regulatory approvals necessary for the sale of drugs may not be obtained when anticipated, or at all, which would reduce or eliminate our potential return on that program.

Before any of our drug candidates can be sold commercially, we or our partners must conduct clinical trials that demonstrate that the drug is safe and effective for use in humans for the indications sought. The results of these clinical trials are used as the basis to obtain regulatory approval from government authorities such as the FDA. Conducting clinical trials is a complex, time-consuming and expensive process that requires an appropriate number of trial sites and patients to support the product label claims being sought. The length of time, number of trial sites and number of patients required for clinical trials vary substantially according to their type, complexity, novelty and the drug candidate’s intended use and therefore, we may spend as much as several years completing certain trials. Further, the time within which we or our partners can complete our clinical trials depends in large part on the ability to enroll eligible patients who meet the enrollment criteria and who are in proximity to the trial sites. We and our partners also face competition with other clinical trials for eligible patients. As a consequence, there may be limited availability of eligible patients, which can result in increased development costs, delays in regulatory approvals and associated delays in drug candidates reaching the market. Patients may also suffer adverse medical events or side effects in the course of clinical trials that may delay or prohibit regulatory approval of our drug candidates. Even if we or our partners successfully conduct clinical trials, we or our partners may not obtain favorable clinical trial results and may not be able to obtain regulatory approval on this basis.

In addition, we plan to conduct further clinical trial activities in territories outside the U.S. through third-party clinical trial service providers that contract with clinical sites and enroll patients in foreign jurisdictions, including Eastern Europe and South America, and may do so in new geographic locations where our experience conducting clinical trials is more limited. Some of these foreign jurisdictions may impose requirements on us or our third-party clinical trial service providers or contract manufacturers that are more stringent than those imposed by the FDA, which may delay the development and approval of our drug candidates.

If we or our partners fail to adequately manage the increasing number, size and complexity of clinical trials, the clinical trials and corresponding regulatory approvals may be delayed or we or our partners may fail to gain approval for our drug candidates altogether. If we or our partners are unable to market and sell our drug candidates or are unable to obtain

approvals in the time frame needed to execute our product strategies, our business and results of operations would be materially adversely affected.

Delays in the commencement or completion of clinical testing could result in increased costs to us and delay or limit our ability to generate revenues.

Delays in the commencement or completion of clinical testing of our products or products of our partners, including any Phase 3 or pivotal trials for MEK162 (partnered with Novartis), ARRY-520, ARRY-614, selumetinib (partnered with AstraZeneca) and danoprevir (partnered with Intermune/Roche Holding AG), could significantly affect our product development costs and our ability to generate revenue from our partnered programs. We do not know whether the FDA will approve the trial designs for ongoing and planned clinical trials or whether planned clinical trials will begin on time or be completed on schedule, if at all. The commencement and completion of clinical trials can be delayed for a number of reasons, including delays related to the ability of Array or our partners to do the following:

Clinical trials may also be delayed as a result of ambiguous or negative interim results. In addition, a clinical trial may be suspended or terminated by us or our partner, the FDA, the IRB overseeing the clinical trial at issue, any of our clinical trial sites with respect to that site, or other regulatory authorities due to a number of factors, including:

Additionally, changes in regulatory requirements and guidance may occur and we may need to amend clinical trial protocols to reflect these changes. Amendments may require us to resubmit our clinical trial protocols to IRBs for reexamination, which may impact the costs, timing or successful completion of a clinical trial. If we experience delays in completion of, or if we terminate, any of our clinical trials, the commercial prospects for our product candidates may be harmed and our ability to generate product revenues will be delayed and/or reduced. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of a product candidate.

Drug candidates that we develop with our partners or on our own may not receive regulatory approval.

The development and commercialization of drug candidates for our partners and our own internal drug discovery efforts are subject to regulation. Pharmaceutical products require lengthy and costly testing in animals and humans and regulatory approval by governmental agencies prior to commercialization. It takes several years to complete testing and failure can occur at any stage of the testing. Results attained in preclinical testing and early clinical trials for any of our drug candidates may not be indicative of results that are obtained in later studies and significant setbacks in advanced clinical trials may arise, even after promising results in earlier studies. Clinical trials may not demonstrate sufficient safety and efficacy to obtain the requisite regulatory approvals or result in marketable products. Furthermore, data obtained from preclinical and clinical studies are susceptible to varying interpretations that may delay, limit or prevent regulatory

approval. In addition, the administration of any drug candidate we develop may produce undesirable side effects or safety issues that could result in the interruption, delay or suspension of clinical trials, or the failure to obtain FDA or other regulatory approval for any or all targeted indications. Based on results at any stage of testing, we or our partners may decide to repeat or redesign a trial or discontinue development of a drug candidate.

Approval of a drug candidate as safe and effective for use in humans is never certain and regulatory agencies may delay or deny approval of drug candidates for commercialization. These agencies may also delay or deny approval based on additional government regulation or administrative action, on changes in regulatory policy during the period of clinical trials in humans and regulatory review or on the availability of alternative treatments. Similar delays and denials may be encountered in foreign countries. None of our partners have obtained regulatory approval to manufacture and sell drug candidates owned by us or identified or developed under an agreement with us. If we or our partners cannot obtain this approval, we will not realize milestone or royalty payments based on commercialization goals for these drug candidates.

 

In light of widely publicized events concerning the safety of certain drug products, such as Avandia® (rosiglitazone), regulatory authorities, members of Congress, the Government Accountability Office, medical professionals and the general public have raised concerns about potential post-marketing drug safety issues. These events have resulted in the withdrawal of drug products, revisions to drug labeling that further limit use of the drug products and establishment of REMS that may, for instance, restrict distribution of drug products and impose burdensome implementation requirements on us. Although drug safety concerns have occurred over time, the increased attention to this issue may result in a more cautious approach by the FDA. As a result, data from clinical trials may receive greater scrutiny with respect to safety than in years past. Safety concerns may result in the FDA or other regulatory authorities terminating clinical trials before completion or requiring longer or additional clinical trials that may result in substantial additional expense and a delay or failure in obtaining approval or approval for a more limited indication than originally sought.

Even if our drug candidates obtain regulatory approval, we and our partners will be subject to ongoing government regulation.

Even if regulatory authorities approve any of our drug candidates, the manufacture, labeling, storage, recordkeeping, reporting, distribution, advertising, promotion, marketing and sale of these drugs will be subject to strict and ongoing regulation. If we, our parters, our product candidates or the manufacturing facilities for our product candidates fail to comply with applicable regulatory requirements, a regulatory agency may suspend any ongoing clinical trials; issue warning letters or untitled letters; suspend or withdraw regulatory approval; refuse to approve pending applications or supplements to applications; suspend or impose restrictions on operations; seize or detain products, prohibit the export or import of products, or require us to initiate a product recall; or seek other monetary or injunctive remedies.

Compliance with ongoing regulation consumes substantial financial and management resources and may expose us and our partners to the potential for other adverse circumstances. For example, approval for a drug may be conditioned on costly post-marketing follow-up studies. Based on these studies, if a regulatory authority does not believe that the drug demonstrates a clinical benefit to patients, it could limit the indications for which a drug may be sold or revoke the drug’s marketing approval. In addition, identification of certain side effects after a drug is on the market may result in the subsequent withdrawal of approval, reformulation of a drug, additional preclinical and clinical trials, changes in labeling or distribution, or we may be required by the FDA to develop and implement a REMS to ensure the safe use of our products. Any of these events could delay or prevent us from generating revenue from the commercialization of these drugs and cause us to incur significant additional costs.

Given the number of high profile safety events with certain drug products, the FDA may require, as a condition of approval, a REMS that includes costly risk management programs with components including safety surveillance, restricted distribution and use, patient education, enhanced labeling, special packaging or labeling, expedited reporting of certain adverse events, pre-approval of promotional materials and restrictions on direct-to-consumer advertising. Furthermore, heightened Congressional scrutiny on the adequacy of the FDA’s drug approval process and the agency’s efforts to assure the safety of marketed drugs has resulted in the proposal of new legislation addressing drug safety issues. If enacted, any new legislation could result in delays or increased costs for manufacturers and drug sponsors during the period of product development, clinical trials and regulatory review and approval, as well as increased costs to assure compliance with any new post-approval regulatory requirements.

In addition, the marketing of these drugs by us or our partners may be heavily scrutinized by the FDA, the Department of Justice, the Department of Health and Human Services' Office of Inspector General, state attorneys general, members of Congress and the public. Our promotional activities will be regulated by federal and state laws pertaining to health care “fraud and abuse,” such as the federal anti-kickback law prohibiting bribes, kickbacks or other remuneration for the order, purchase or recommendation of items or services reimbursed by federal health care programs. Many states have similar

laws applicable to items or services reimbursed by commercial insurers. Violations of fraud and abuse laws can result in costly litigation, fines and/or imprisonment or exclusion from participation in federal health care programs and burdensome reporting and compliance obligations.

If our drug candidates do not gain market acceptance, we may be unable to generate significant revenue.

Even if our drug candidates are approved for sale, they may not be successful in the marketplace. Market acceptance of any of our drug candidates will depend on a number of factors including:

If our drug candidates do not gain market acceptance among physicians, patients and others in the medical community, our ability to generate meaningful revenues from our drug candidates would be limited.

Our cGMP and pharmacology facilities and practices may fail to comply with government regulations.

All facilities and manufacturing processes used in the production of API, and drug products for clinical use in the U.S., must be operated in conformity with cGMP as established by the FDA. Similar requirements in other countries exist for manufacture of drug products for clinical use. These requirements include, among other things, quality control, quality assurance and the maintenance of records and documentation. If we or any contract manufacturers we use fail to comply with these requirements, we may not be able to continue the production of our products and we could be subject to civil and criminal fines and penalties, suspension of production, suspension or delay in product approval, product seizure or recall, or withdrawal of product approval. We operate a clinical-scale manufacturing facility that we believe conforms to cGMP requirements. This facility and our cGMP practices may be subject to periodic regulatory inspections to ensure compliance with cGMP requirements. In addition, we could be required to comply with specific requirements or specifications of other countries and/or of our partners, which may exceed applicable regulatory requirements. Failure on our part to comply with applicable regulations and specific requirements or specifications of other countries and/or our partners could result in the termination of ongoing research, disqualification of data for submission to regulatory authorities, delays or denials of new product approvals, warning letters, fines, consent decrees restricting or suspending manufacturing operations, injunctions, civil penalties, recall or seizure of products and criminal prosecution. Material violations of cGMP requirements could result in regulatory sanctions and, in severe cases, could result in a mandated closing of our cGMP facility.

In connection with our application for commercial approvals and, if any drug candidate is approved by the FDA or other regulatory agencies for commercial sale, a significant scale-up in manufacturing may require additional validation studies. If we are unable to successfully increase the manufacturing capacity for a drug candidate, the regulatory approval or commercial launch of that drug candidate may be delayed, or there may be a shortage of supply, which could limit our ability to develop or commercialize the drug.

In addition, our pharmacology facility may be subject to FDA Good Laboratory Practices, or GLP, and United States Department of Agriculture, or USDA, regulations for certain animal species. Failure on our part to comply with applicable regulations and specific requirements of our partners could result in the termination of ongoing pharmacology research. Material violations of GLP and USDA requirements could result in additional regulatory sanctions and, in severe cases, could result in a mandated closing of our pharmacology facility for certain species.

We or third-party manufacturers we rely on may encounter failures or difficulties in manufacturing or formulating clinical commercial supplies of drugs, which could delay the clinical development or regulatory approval of our drug candidates, or their ultimate commercial production if approved.

We and third parties manufacture our drug candidates. We also from time to time manufacture drug candidates for our partners. We do not have manufacturing facilities that can produce sufficient quantities of API and finished drug product for large-scale clinical trials. We frequently contract with third-party manufacturers to produce larger quantities of API for us. Some of these manufacturers are located outside the U.S. and may obtain ingredients from suppliers in other foreign countries before shipping the bulk API to Array in the U.S. Cross-border shipments of pharmaceutical ingredients and

products are subject to regulation in the U.S. by the FDA and in foreign jurisdictions, including, in the EU, under laws adopted by the EU Member States implementing the Community Code on Medicinal Products Directive 2001/83, as amended. These foreign regulations generally impose various requirements on us and/or our third-party manufacturers. In some cases, for example in the EU, there are cGMP requirements that exceed the requirements of the FDA. In other cases, we must provide confirmation that we are registered with the FDA and have either a Notice of Claimed Investigational Exemption for a New Drug or IND application or an approved NDA. Third-party manufacturers may lack capacity to meet our needs, go out of business or fail to perform. In addition, supplies of raw materials needed for manufacturing or formulation of clinical supplies may not be available or in short supply.

Accordingly, we must either develop such facilities, which will require substantial additional funds, or rely, at least to some extent, on third-party manufacturers for the production of drug candidates. Furthermore, should we obtain FDA approval for any of our drug candidates, we expect to rely, at least to some extent, on third-party manufacturers for commercial production. Our dependence on others for the manufacture of our drug candidates may adversely affect our ability to develop and deliver such drug candidates on a timely and competitive basis.

Any performance failure on the part of us or a third-party manufacturer could delay clinical development, regulatory approval or, ultimately, sales of our or our partners’ drug candidates. We or third-party manufacturers may encounter difficulties involving production yields, regulatory compliance, lot release, quality control and quality assurance, as well as shortages of qualified personnel. Approval of our drug candidates could be delayed, limited or denied if the FDA does not approve our or a third-party manufacturer’s processes or facilities. Moreover, the ability to adequately and timely manufacture and supply drug candidates is dependent on the uninterrupted and efficient operation of the manufacturing facilities, which is impacted by many manufacturing variables including:

In addition, we or our third-party manufacturers may encounter delays and problems in manufacturing our drug candidates or drugs for a variety of reasons, including accidents during operation, failure of equipment, delays in receiving materials, natural or other disasters, political or governmental changes, or other factors inherent in operating complex manufacturing facilities. Supply chain management is complex, and involves sourcing from a number of different companies and foreign countries. Commercially available starting materials, reagents and excipients may become scarce or more expensive to procure, and we may not be able to obtain favorable terms in agreements with subcontractors. We or our third-party manufacturers may not be able to operate our respective manufacturing facilities in a cost-effective manner or in a time frame that is consistent with our expected future manufacturing needs. If we or our third-party manufacturers cease or interrupt production or if our third-party manufacturers and other service providers fail to supply materials, products or services to us for any reason, such interruption could delay progress on our programs, or interrupt the commercial supply, with the potential for additional costs and lost revenues. If this were to occur, we may also need to seek alternative means to fulfill our manufacturing needs.

We may not be able to enter into agreements for the manufacture of our drug candidates with manufacturers whose facilities and procedures comply with applicable law. Manufacturers are subject to ongoing periodic unannounced inspection by the FDA, the Drug Enforcement Agency, or DEA, and corresponding state and foreign authorities to ensure strict compliance with cGMP and other applicable government regulations and corresponding foreign standards. We do not have control over a third-party manufacturer’s compliance with these regulations and standards. If we or one of our manufacturers fail to maintain compliance, we or they could be subject to civil or criminal penalties, the production of our drug candidates could be interrupted or suspended, or our product could be recalled or withdrawn, resulting in delays, additional costs and potentially lost revenues.

Our development, testing and manufacture of drug candidates may expose us to product liability and other lawsuits.

We develop, test and manufacture drug candidates that are generally intended for use in humans. Our drug discovery and development activities, including clinical trials we or our partners conduct, that result in the future manufacture and sale of drugs by us or our partners expose us to the risk of liability for personal injury or death to persons using these drug candidates. We may be required to pay substantial damages or incur legal costs in connection with defending any of these product liability claims, or we may not receive revenue from expected royalty or milestone payments if the commercialization of a drug is limited or ceases as a result of such claims. We have product liability insurance that contains customary exclusions and provides coverage up to $10 million per occurrence and in the aggregate, which we believe is customary in our industry for our current operations. However, our product liability insurance does not cover every type of product liability claim that we may face or loss we may incur and may not adequately compensate us for the entire amount of covered claims or losses or for the harm to our business reputation. We may be unable to acquire additional or maintain our current insurance policies at acceptable costs or at all.

Due to our reliance on CROs and other third parties to conduct our clinical trials, we are unable to directly control the timing, conduct and expense of our clinical trials.

We rely primarily on third parties to manufacture API and drug product and to conduct our clinical trials. As a result, we have had and will continue to have less control over the conduct of our clinical trials, the timing and completion of the trials, the required reporting of adverse events and the management of data developed through the trial than would be the case if we were relying entirely upon our own staff. Communicating with outside parties can also be challenging, potentially leading to mistakes, as well as difficulties in coordinating activities. Outside parties may have staffing difficulties, may undergo changes in priorities or may become financially distressed, adversely affecting their willingness or ability to conduct our trials. We may experience unexpected cost increases that are beyond our control. Problems with the timeliness or quality of the work of a contract manufacturing or contract research organization may lead us to seek to terminate the relationship and use an alternative service provider. However, making this change may be costly and may delay our trials and contractual restrictions may make such a change difficult or impossible. Additionally, it may be impossible to find a replacement organization that can conduct our trials in an acceptable manner and at an acceptable cost.

Controls we or our third-party service providers have in place to ensure compliance with laws may not be effective to ensure compliance with all applicable laws and regulations.

The discovery and development of our products, together with our general operations, are subject to extensive regulation in the U.S. by state and federal agencies and in foreign countries. Due to escalating costs and difficulties associated with conducting certain types of clinical trials in the U.S., we conduct certain clinical trials in foreign locations where we have little experience, including countries in Eastern Europe and South America. We expect that we typically will conduct these trials through third-party clinical trial service providers. In addition, we purchase from third-party suppliers and manufacturers that are located outside the U.S., principally countries in Europe, intermediate and bulk API that are used in our development efforts and we contract with third-party service providers to prepare finished drug product, including packaging and labeling. As a result, we and our contractors are subject to regulations in the U.S. and in the foreign countries in which the API is sourced and manufactured relating to the cross-border shipment of pharmaceutical ingredients. Although we have developed and instituted controls, we, our employees, our consultants or our contractors may not be in compliance with all potentially applicable U.S. federal and state regulations and/or laws or all potentially applicable foreign regulations and/or laws. Further, we have a limited ability to monitor and control the activities of third-party service providers, suppliers and manufacturers to ensure compliance by such parties with all applicable regulations and/or laws. We may be subject to direct liabilities or be required to indemnify such parties against certain liabilities arising out of any failure by them to comply with such regulations and/or laws. If we or our employees, consultants or contractors fail to comply with any of these regulations and/or laws a range of actions could result, including, but not limited to, the termination of clinical trials, the failure to approve a product candidate, restrictions on our products or manufacturing processes, including withdrawal of our products from the market, significant fines, exclusion from government healthcare programs or other sanctions or litigation.

If our use of chemical and hazardous materials violates applicable laws or regulations or causes personal injury we may be liable for damages.

Our drug discovery activities, including the analysis and synthesis of chemical compounds, involve the controlled use of chemicals, including flammable, combustible, toxic and radioactive materials that are potentially hazardous. Our use, storage, handling and disposal of these materials is subject to federal, state and local laws and regulations, including the

Resource Conservation and Recovery Act, the Occupational Safety and Health Act and local fire codes and regulations promulgated by the Department of Transportation, the DEA, the Department of Energy, the Colorado Department of Public Health and Environment and the Colorado Department of Human Services, Alcohol and Drug Abuse Division. We may incur significant costs to comply with these laws and regulations in the future. In addition, we cannot completely eliminate the risk of accidental contamination or injury from these materials, which could result in material unanticipated expenses, such as substantial fines or penalties, remediation costs or damages, or the loss of a permit or other authorization to operate or engage in our business. Those expenses could exceed our net worth and limit our ability to raise additional capital.

Our operations could be interrupted by damage to our specialized laboratory facilities.

Our operations depend on the continued use of our highly specialized laboratories and equipment in Boulder and Longmont, Colorado. Catastrophic events, including fires or explosions, could damage our laboratories, equipment, scientific data, work in progress or inventories of chemical compounds and may materially interrupt our business. We employ safety precautions in our laboratory activities in order to reduce the likelihood of the occurrence of these catastrophic events; however, we cannot eliminate the chance that such an event will occur. The availability of laboratory space in these locations is limited and rebuilding our facilities could be time consuming and result in substantial delays in fulfilling our agreements with our partners. We maintain business interruption insurance in the amount of $15 million to cover continuing expenses and lost revenue caused by such occurrences. However, this insurance does not compensate us for the loss of opportunity and potential harm to customer relations that our inability to meet our partners’ needs in a timely manner could create.

Risks Related to Our Drug Discovery Activities

Revenue from collaborations depends on the extent to which the pharmaceutical and biotechnology industries collaborate with other companies for one or more aspects of their drug discovery process.

Our capabilities include aspects of the drug discovery process that pharmaceutical and biotechnology companies have traditionally performed internally. The willingness of these companies to expand or continue drug discovery collaborations to enhance their research and development process is based on several factors that are beyond our control, any of which could cause our revenue to decline. These include their ability to hire and retain qualified scientists, the resources available for entering into drug discovery collaborations and the spending priorities among various types of research activities. In addition, our ability to convince these companies to use our drug discovery capabilities, rather than develop them internally, depends on many factors, including our ability to:

The importance of these factors varies depending on the company and type of discovery program and we may be unable to meet any or all of them in the future. Even if we are able to address these factors, these companies may still decide to perform these activities internally or retain other companies that provide drug research and development expertise similar to ours.

Our research and development capabilities may not produce viable drug candidates.

We have entered into several research and development collaborations under which we provide drug discovery and development services to identify drug candidates for our partners. We also seek to identify and develop drug candidates for our proprietary programs. It is uncertain whether we will be able to provide drug discovery more efficiently or create high quality drug candidates that are suitable for our or our partners' purposes, which may result in delayed or lost revenue, loss of partners or failure to expand our existing relationships. Our ability to create viable drug candidates for ourselves and our partners depends on many factors, including the implementation of appropriate technologies, the development of effective new research tools, the complexity of the chemistry and biology, the lack of predictability in the scientific process and the performance and decision-making capabilities of our scientists. Our information-driven technology platform, which we believe allows our scientists to make better decisions, may not enable our scientists to make correct decisions or develop viable drug candidates.

Risks Related to Our Industry

The concentration of the pharmaceutical and biotechnology industry and any further consolidation could reduce the number of our potential partners.

There are a limited number of pharmaceutical and biotechnology companies and these companies represent a significant portion of the market for our capabilities. The number of our potential partners could decline even further through consolidation among these companies. If the number of our potential partners declines even further, they may be able to negotiate greater rights to the intellectual property they license from us, price discounts or other terms that are unfavorable to us.

Capital market conditions may reduce our biotechnology partners' ability to fund research and development.

Traditionally, many unprofitable biotechnology companies have funded their research and development expenditures through raising capital in the debt and equity markets. These markets have historically been volatile and declines in these markets may severely restrict their ability to raise new capital and to continue to expand or fund existing research and development efforts. If our current or future biotechnology partners are unable to raise sufficient capital to fund research and development expenditures, we may not be able to expand or maintain current revenue.

Health care reform, including those based on recently enacted legislation and cost control initiatives by third-party payors, could reduce the prices that can be charged for drugs, which could limit the commercial success of our drug candidates.

The Patient Protection and Affordable Care Act and the Health Care and Education Reconciliation Act of 2010, together the "Healthcare Reform Act" substantially changes the way health care is financed by both governmental and private insurers and significantly impacts the pharmaceutical industry. The Healthcare Reform Act contains a number of provisions that are expected to impact our business and operations, in some cases in ways we cannot currently predict. Changes that may affect our business include those governing enrollment in federal healthcare programs, mandatory discounts on pharmaceuticals under federal health care programs, reimbursement changes, rules regarding prescription drug benefits under the health insurance exchanges, and fraud and abuse enforcement. In addition, continued implementation of the Healthcare Reform Act may result in the expansion of new programs such as Medicare payment for performance initiatives, and may impact existing government healthcare programs, such as by improving the physician quality reporting system and feedback program.

Additional provisions of the Healthcare Reform Act may negatively affect any revenues from products we or our partners are able to commercialize in the future. For example, as part of the Healthcare Reform Act’s provisions closing a coverage gap that currently exists in the Medicare Part D prescription drug program, manufacturers of branded prescription drugs are required to provide a 50% discount on drugs dispensed to beneficiaries within this coverage gap. Healthcare reform also expanded the number of safety net providers and hospitals that receive discounted pricing on outpatient medicines under the 340B program discussed further herein, which may result in manufacturers being required to sell more drugs at the discounted 340B price, and could have a material adverse effect on the sales and revenues of commercialized products.

Many of the Healthcare Reform Act's most significant reforms do not take effect until 2014 and thereafter, and their details will be shaped significantly by implementing regulations, some of which have yet to be finalized. In 2012, the Supreme Court of the United States heard challenges to certain provisions of the Healthcare Reform Act. The Supreme Court’s decision upheld most of the Healthcare Reform Act; however, the Supreme Court struck down a provision in the Healthcare Reform Act that penalized states that chose not to expand their Medicaid programs through an increase in the Medicaid eligibility income limit from a state’s current eligibility levels to 133% of the federal poverty limit. As a result of the Supreme Court’s ruling, it is unclear how many states will expand their Medicaid programs by raising the income limit to 133% of the federal poverty level and whether there will be more uninsured patients in 2014 than anticipated when Congress passed the Healthcare Reform Act. For each state that does not expand its Medicaid program, there will be fewer insured patients overall. An increase in the proportion of uninsured patients who are prescribed products resulting from our proprietary or partnered programs could impact future sales of any products that are commercialized in the future and our business and results of operations. Where patients receive insurance coverage under any of the new options made available through the Healthcare Reform Act, the possibility exists that manufacturers may be required to pay Medicaid rebates on that resulting drug utilization, a decision that could impact manufacturer revenues. In addition, the Administration has also announced delays in the implementation of key provisions of the Healthcare Reform Act. The implications of these delays for our sales, business and financial condition, if any, are not yet clear.

Moreover, legislative changes to the Healthcare Reform Act remain possible. We expect that the Healthcare Reform Act, as currently enacted and as may be amended in the future, and other healthcare reform measures that may be adopted in the future could have a material adverse effect on our industry generally and on the ability of Array or our partners to successfully commercialize product candidates or could limit or eliminate our future spending on development projects.

In addition to the Healthcare Reform Act, there will continue to be proposals by legislators at both the federal and state levels, regulators and third-party payors to keep healthcare costs down while expanding individual healthcare benefits. Certain of these changes could limit the prices that can be charged for drugs we develop or the amounts of reimbursement available for these products from governmental agencies or third-party payors, or may increase the tax obligations on pharmaceutical companies, or may facilitate the introduction of generic competition with respect to products we are able to commercialize, and so may limit our commercial opportunity and reduce any associated revenue and profits.

In some countries other than the U.S., reimbursement, pricing and profitability of prescription pharmaceuticals and biopharmaceuticals are subject to government control. We are unable to predict what additional legislation or regulation, if any, relating to the healthcare industry or third-party coverage and reimbursement may be enacted in the future or what effect such legislation or regulation would have on our business.

Also, we expect managed care plans will continue to put pressure on the pricing of pharmaceutical and biopharmaceutical products due to a trend toward managed health care, the increasing influence of health maintenance organizations and additional legislative proposals. Cost control initiatives could decrease the price that we, or any potential partners, receive for any of our future products, which could adversely affect our profitability. These initiatives may also have the effect of reducing the resources that pharmaceutical and biotechnology companies can devote to in-licensing drug candidates and the research and development of new drugs, which could reduce our resulting revenue. Any cost containment measures or other reforms that are adopted could have a negative impact on our ability to commercialize successfully our products or could limit or eliminate our spending on development of new drugs and affect our profitability.

Other legislation affecting government expenditures more broadly have the potential to affect negatively our product revenues and prospects for continued profitability. For example, beginning April 1, 2013, Medicare payments for all items and services, including drugs and biologicals, have been reduced by 2% under the sequestration (i.e., automatic spending reductions) required by the Budget Control Act of 2011, Pub. L. No. 112-25, or BCA, as amended by the American Taxpayer Relief Act of 2012, Pub. L. 112-240, or ATRA. The BCA requires sequestration for most federal programs, excluding Medicaid, Social Security, and certain other programs, because Congress failed to enact legislation by January 15, 2012, to reduce federal deficits by $1.2 trillion over ten years. These cuts could adversely impact payment for products that we or our partners are able to commercialize, which could negatively impact our revenue.

We, or our partners, may not obtain favorable reimbursement rates for our drug candidates.

The commercial success of our drug candidates will depend on the availability and adequacy of coverage and reimbursement from third-party payors, including government and private insurance plans. Third-party payors are increasingly challenging the prices charged for pharmaceuticals and other medical products. Our products may be considered less cost-effective than existing products and, as such, coverage and reimbursement to the patient may not be available or be sufficient to allow the sale of our products on a competitive basis or on a profitable basis.

In addition, the market for our drug candidates will depend significantly on access to third-party payors’ drug formularies, or lists of medications for which third-party payors provide coverage and reimbursement. Industry competition to be included in such formularies can result in downward pricing pressures on pharmaceutical companies. As such, we cannot provide assurances that our products will be placed on third-party payors' formularies. To the extent that our products are listed on third-party payors' formularies, we or our partners may not be able to negotiate favorable reimbursement rates for our products. If we, or our partners, fail to obtain an adequate level of reimbursement for our products by third-party payors, sales of the drugs would be adversely affected or there may be no commercially viable market for the products.

Payors also are increasingly considering new metrics as the basis for reimbursement rates, such as average sales price, or ASP, average manufacturer price, or AMP, and Actual Acquisition Cost. The existing data for reimbursement based on some of these metrics is relatively limited, although certain states have begun to survey acquisition cost data for the purpose of setting Medicaid reimbursement rates, and CMS has begun making pharmacy National Average Drug Acquisition Cost and National Average Retail Price data publicly available on at least a monthly basis. Therefore, it may be difficult to project the impact of these evolving reimbursement mechanics on the willingness of payors to cover candidate products that we or our partners are able to commercialize. As discussed below, to the extent that we or our partners participate in government pricing programs, recent legislative changes to the 340B drug pricing program, the

Medicaid Drug Rebate Program, and the Medicare Part D prescription drug benefit also could impact our revenues. We anticipate that a significant portion of revenue from sales of drugs that we or our partners are able to commercialize may be obtained through government payors, including Medicaid, and any failure to qualify for reimbursement for those products under those programs would have a material adverse effect on our sales revenues and royalties.

The drug research and development industry has a history of patent and other intellectual property litigation and we may be involved in costly intellectual property lawsuits.

The drug research and development industry has a history of patent and other intellectual property litigation and we believe these lawsuits are likely to continue. Legal proceedings relating to intellectual property would be expensive, take significant time and divert management's attention from other business concerns. Because we produce drug candidates for a broad range of therapeutic areas and provide many different capabilities in this industry, we face potential patent infringement suits by companies that control patents for similar drug candidates or capabilities or other suits alleging infringement of their intellectual property rights. There could be issued patents of which we are not aware that our products infringe or patents that we believe we do not infringe that we are ultimately found to infringe. Moreover, patent applications are in many cases maintained in secrecy for 18 months after filing or even until patents are issued. The publication of discoveries in the scientific or patent literature frequently occurs substantially later than the date on which the underlying discoveries were made and patent applications were filed. Because patent applications can take many years to issue, there may be currently pending applications of which we are unaware that may later result in issued patents that we infringe with our products. In addition, technology created under our research and development collaborations may infringe the intellectual property rights of third parties, in which case we may not receive milestone or royalty revenue from those collaborations.

If we do not prevail in an infringement lawsuit brought against us, we might have to pay substantial damages, including triple damages, and we could be required to stop the infringing activity or obtain a license to use the patented technology or redesign our products so as not to infringe the patent. We may not be able to enter into licensing arrangements at a reasonable cost or effectively redesign our products. Any inability to secure licenses or alternative technology could delay the introduction of our products or prevent us from manufacturing or selling products.

The intellectual property rights we rely on to protect our proprietary drug candidates and the technology underlying our tools and techniques may be inadequate to prevent third parties from using our technology or developing competing capabilities or to protect our interests in our proprietary drug candidates.

Our success depends in part on our ability to protect patents and maintain the secrecy of proprietary processes and other technologies we develop for the testing and synthesis of chemical compounds in the drug discovery process. We currently have numerous U.S. patents and patent applications on file with the U.S. Patent and Trademark Office, as well as around the world.

Any patents that we may own or license now or in the future may not afford meaningful protection for our drug candidates or our technology and tools. In order to protect or enforce our intellectual property rights, we may have to initiate legal proceedings against third parties. Our efforts to enforce and maintain our intellectual property rights may not be successful and may result in substantial costs and diversion of management time. In addition, other companies may challenge our patents and, as a result, these patents could be narrowed, invalidated or deemed unenforceable, or we may be forced to stop using the technology covered by these patents or to license the technology from third parties. In addition, current and future patent applications on which we depend may not result in the issuance of patents in the U.S. or foreign countries. Even if our rights are valid, enforceable and broad in scope, competitors may develop drug candidates or other products based on similar research or technology that is not covered by our patents.

Patent applications relating to or affecting our business may have been filed by a number of pharmaceutical and biopharmaceutical companies and academic institutions. A number of the technologies in these applications or patents may conflict with our technologies, patents or patent applications, which could reduce the scope of patent protection we could otherwise obtain. We could also become involved in interference proceedings in connection with one or more of our patents or patent applications to determine priority of inventions. We cannot be certain that we are the first creator of inventions covered by pending patent applications, or that we were the first to file patent applications for any such inventions.

Drug candidates we develop that are approved for commercial marketing by the FDA would be eligible for market exclusivity for varying time periods during which generic versions of a drug may not be marketed and we could apply to extend patent protection for up to five additional years under the provisions of the Hatch-Waxman Act. The Hatch-Waxman Act provides a means for approving generic versions of a drug once the marketing exclusivity period has ended

and all relevant patents have expired. The period of exclusive marketing, however, may be shortened if a patent is successfully challenged and defeated, which could reduce the amount of royalties we receive on the product.

Agreements we have with our employees, consultants and partners may not afford adequate protection for our trade secrets, confidential information and other proprietary information.

In addition to patent protection, we also rely on copyright and trademark protection, trade secrets, know-how, continuing technological innovation and licensing opportunities. In an effort to maintain the confidentiality and ownership of our trade secrets and proprietary information, we require our employees, consultants and advisors to execute confidentiality and proprietary information agreements. However, these agreements may not provide us with adequate protection against improper use or disclosure of confidential information and there may not be adequate remedies in the event of unauthorized use or disclosure. The failure by employees, consultants or advisors to maintain the secrecy of our confidential information may compromise or prevent our ability to obtain needed or meaningful patent protection. Furthermore, we may from time to time hire scientific personnel formerly employed by other companies involved in one or more areas similar to the activities we conduct. In some situations, our confidentiality and proprietary information agreements may conflict with, or be subject to, the rights of third parties with whom our employees, consultants or advisors have prior employment or consulting relationships. Although we require our employees and consultants to maintain the confidentiality of all proprietary information of their previous employers, these individuals, or we, may be subject to allegations of trade secret misappropriation or other similar claims as a result of their prior affiliations. Finally, others may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets. Our failure or inability to protect our proprietary information and techniques may inhibit or limit our ability to compete effectively, or exclude certain competitors from the market.

The drug research and development industry is highly competitive and we compete with some companies that offer a broader range of capabilities and have better access to resources than we do.

The pharmaceutical and biotechnology industries are characterized by rapid and continuous technological innovation. We compete with many companies worldwide that are engaged in the research and discovery, licensing, development and commercialization of drug candidates. Some of our competitors have a broader range of capabilities and have greater access to financial, technical, scientific, regulatory, business development, recruiting and other resources than we do. Their access to greater resources may allow them to develop processes or products that are more effective, safer or less costly, or gain greater market acceptance, than products we develop or for which they obtain FDA approval more rapidly than we do. We anticipate that we will face increased competition in the future as new companies enter the market and advanced technologies become available.

We face potential liability related to the privacy of health information we obtain from research institutions.

Most health care providers, including research institutions from which we or our partners obtain patient information, are subject to privacy and security regulations promulgated under HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act. Our clinical research efforts are not directly regulated by HIPAA. However, conduct by a person that may not be prosecuted directly under HIPAA's criminal provisions could potentially be prosecuted under aiding and abetting or conspiracy laws. Consequently, depending on the facts and circumstances, we could face substantial criminal penalties if we knowingly receive individually identifiable health information from a health care provider or research institution that has not satisfied HIPAA's disclosure standards. In addition, international data protection laws including the EU Data Protection Directive and member state implementing legislation may apply to some or all of the clinical data obtained outside of the U.S. Furthermore, certain privacy laws and genetic testing laws may apply directly to our operations and/or those of our partners and may impose restrictions on our use and dissemination of individuals' health information. Moreover, patients about whom we or our partners obtain information, as well as the providers who share this information with us, may have contractual rights that limit our ability to use and disclose the information. Claims that we have violated individuals' privacy rights or breached our contractual obligations, even if we are not found liable, could be expensive and time-consuming to defend and could result in adverse publicity that could harm our business.

Pharmaceutical companies are subject to significant ongoing health care regulatory obligations and oversight, which may result in significant additional expense and limit our or their ability to commercialize our products.

If we or any partners fail to comply with applicable federal, state, or local regulatory requirements, we could be subject to a range of regulatory actions that could affect our or any partners' ability to commercialize our products and could harm or prevent sales of any affected products that we are able to commercialize, or could substantially increase the costs and expenses of commercializing and marketing our products. Any threatened or actual government enforcement action

could also generate adverse publicity and require that we devote substantial resources that could otherwise be used in other aspects of our business.

Risks Related to Our Stock

Our quarterly operating results could fluctuate significantly, which could cause our stock price and the value of the 2020 notes to decline.

Our quarterly operating results have fluctuated in the past and are likely to fluctuate in the future. Entering into partnerships typically involves significant technical evaluation and/or commitment of capital by our partners. Accordingly, negotiation can be lengthy and is subject to a number of significant risks, including partners' budgetary constraints and internal acceptance reviews and a significant portion of our revenue from these partnerships is attributable to up-front payments and milestones that are non-recurring. Further, some of our partners can influence when we deliver products and perform services or milestones are achieved and, therefore, when we receive revenue, under their contracts with us. Due to these factors, our operating results could fluctuate significantly from quarter to quarter. In addition, we may experience significant fluctuations in quarterly operating results due to factors such as general and industry-specific economic conditions that may affect the research and development expenditures of pharmaceutical and biotechnology companies.

Due to the possibility of fluctuations in our revenue and expenses, we believe that quarter-to-quarter comparisons of our operating results are not a good indication of our future performance. Our operating results in some quarters may not meet the expectations of stock market analysts and investors. If we do not meet analysts' and/or investors' expectations, our stock price and the value of our 2020 notes could decline.

Because our stock price may be volatile, our stock price and the value of our 2020 notes could experience substantial declines.

The market price of our common stock has historically experienced and may continue to experience volatility. The high and low sales prices for our common stock were $6.56 and $3.25, respectively, during fiscal 2013 ; $4.10 and $1.58, respectively, during fiscal 2012 ; and $3.60 and $2.05, respectively, during fiscal 2011 . Our quarterly operating results, the success or failure of our internal drug discovery efforts, decisions to delay, modify or cease one or more of our development programs, negative data or adverse events reported on programs in clinical trials we or our partners are conducting, uncertainties about our ability to continue to fund our operating plan, changes in general conditions in the economy or the financial markets and other developments affecting our partners, our competitors or us could cause the market price of our common stock to fluctuate substantially. This volatility coupled with market declines in our industry over the past several years have affected the market prices of securities issued by many companies, often for reasons unrelated to their operating performance, and may adversely affect the price of our common stock and the value of our 2020 notes. In the past, securities class action litigation has often been instituted following periods of volatility in the market price of a company's securities. A securities class action suit against us could result in potential liabilities, substantial costs and the diversion of management's attention and resources, regardless of whether we win or lose.

Because we do not intend to pay dividends, stockholders will benefit from an investment in our common stock only if it appreciates in value.

We have never declared or paid any cash dividends on our common stock and are restricted in our ability to do so under our Loan and Security Agreement with Comerica Bank. We currently intend to retain our future earnings, if any, to finance the expansion of our business and do not expect to pay any cash dividends in the foreseeable future. As a result, the success of an investment in our common stock will depend entirely upon any future appreciation. There is no guarantee that our common stock will appreciate in value or even maintain the price at which stockholders have purchased their shares.

Certain provisions in the 2020 notes and the related indenture as well as Delaware law and our organizational documents could delay or prevent an otherwise beneficial takeover or takeover attempt of us, which may not be in the best interests of our stockholders.

Certain provisions in the 2020 notes and the indenture, as well as certain provisions of Delaware law and our organizational documents could make it more difficult or more expensive for a third party to acquire us. For example, if an acquisition event constitutes a fundamental change, holders of the 2020 notes will have the right to require us to purchase their notes in cash. In addition, if an acquisition event constitutes a make-whole fundamental change, we may be required

to increase the conversion rate for holders who convert their 2020 notes in connection with such make-whole fundamental change.

Delaware law prohibits, subject to certain exceptions, a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years following the date that the stockholder became an interested stockholder. Additionally, our certificate of incorporation and bylaws contain provisions that could similarly delay, defer or discourage a change in control of us or management. These provisions could also discourage a proxy contest and make it more difficult for stockholders to elect directors and take other corporate actions. Such provisions provide for the following, among other things: (i) the ability of our Board of Directors to issue shares of common stock and preferred stock without stockholder approval; (ii) the ability of our Board of Directors to establish the rights and preferences of authorized and unissued preferred stock; (iii) a Board of Directors divided into three classes of directors serving staggered three year terms; (iv) permitting only the Chairman of the Board of Directors, the Chief Executive Officer, the president or the Board of Directors to call a special meeting of stockholders; and (v) requiring advance notice of stockholder proposals and related information. In any of these cases, and in other cases, our obligations under the 2020 notes and the indenture, as well as provisions of Delaware law and our organizational documents and other agreements could increase the cost of acquiring us or otherwise discourage a third party from acquiring us or removing incumbent management.